Systems

Create the RAM disk:

diskutil erasevolume HFS+ "ramdisk" `hdiutil attach -nomount ram://1165430`

(the magic number 1165430 is explained here as the number of 512 byte sectors. The string "ramdisk" is just the name of the disk, which will appear under /Volumes after creation)

Write some stuff to the RAM disk:

echo "hello RAM disk" > /Volumes/ramdisk/hello.txt

Eject the RAM disk:

diskutil eject /Volumes/ramdisk

Gathered from here and here so that I remember for later.

On Linux

Found this guide for creating a RAM disk on Linux, but have not tried it yet.

Prepare the database by installing PL/Python and a function:

CREATE EXTENSION IF NOT EXISTS plpythonu;
 
CREATE OR REPLACE FUNCTION hello_lp()
  RETURNS FLOAT[]
AS $$
  import subprocess
  output = subprocess.Popen (
    [
     "/Library/Frameworks/Python.framework/Versions/2.7/bin/python", 
     "/usr/local/trystuff/hello_lp.py"
    ], 
    stdout = subprocess.PIPE, 
    stderr = subprocess.STDOUT
  ).communicate()[0]
  # Parse string OF comma-separated floats
  RETURN map(lambda x: FLOAT(x), output.split(","))
$$ LANGUAGE plpythonu;

Install LP-solver (cvxopt):

pip install cvxopt

External Python script (save as /usr/local/trystuff/hello_lp.py):

from cvxopt import matrix, solvers
 
solvers.options['show_progress'] = False
 
A = matrix([ [-1.0, -1.0, 0.0, 1.0], [1.0, -1.0, -1.0, -2.0] ])
b = matrix([ 1.0, -2.0, 0.0, 4.0 ])
c = matrix([ 2.0, 1.0 ])
sol=solvers.lp(c,A,b)
 
# Print string of comma-separated floats
print ",".join([str(x) for x in sol['x']])

Try it:

SELECT unnest(hello_lp());

Here is a project I'm working on called the Web Co-Processor (credit for name goes to Marcos Vaz Salles). There is a demo you can try if you clone the project.

Read the following four bullets and you'll understand what the web co-processor is about:

1. A person opens a webpage in his browser
2. The webpage has a small javascript code that opens a two-way connection between the browser and the server using a websocket
3. The persons browser is now a core in the web co-processor
4. A core can execute javascript on behalf of other web cores (or the server), and store transient data

If you are thinking botnet, you are forgiven. The idea is similar, but the intent different. Although I came up with the idea independently, I have found out that other people have thought about similar ideas before.

I'm serious about this idea. I think the idea of massive numbers of transient cores and memory offer some very interesting challenges. I'm keeping a lid on the ideas I have for the web co-processor, but you can follow my github repostitory to get updates as stuff happens. Action is expected to be sporadic but relatively intense.

Feel free to clone github.com/skipperkongen/webcoprocessor.

git clone git@github.com:skipperkongen/webcoprocessor.git

As the title says, this post is just a filtering of todays proggit. Namely the posts that caught my interest that day.

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